performancecontrol: add COMMON_VDD_PATH

in some kernels the VDD table could be located in a common cpu folder instead of cpu0, cpu1 etc each folder

Change-Id: I3ec574fdb5fe46850e8e42ec415712fb71893174
Signed-off-by: ChampionSwimmer <android@championswimmer.tk>
Merge remote-tracking branch 'upstream/jb-mr1' into jb-mr1